Photo-chemical production of oximes

ABSTRACT

A HIGH-PRESSURE MERCURY VAPOUR DISCHARGE LAMP FOR CARRYING OUT PHOTO-CHEMICAL REACTIONS COMPRISES AN ENVELOPE DEFINING AN ENCLOSED SPACE, THE ENCLOSED SPACE HAVING THEREIN A DOPING MEDIUM COMPRISING AT LEAST ONE HALIDE OF A METAL OF GROUP 6 (SUCH AS CHROMIUM), WITH WHICH THERE MAY BE ASSOCIATED A HALIDE OF A METAL OF GROUP 3 ( SUCH AS YTTRIUM) AND/OR A HALIDE OF A METAL OF THE LANTHANIDE GROUP (SUCH AS HOLMIUM), THE CONCENTRATION OF THE DOPING MEDIUM BEING FROM 0.002 TO MG./CC. AND PREFERABLY FROM 0.02 TO 0.5 MG/CC.

3,681,217 PHOTO-CHEMICAL PRODUCTION OF OXIMES Georges Lucas, Paris, and Claude Viallet, Pau, France, assignors to Societe Nationale des Petroles dAquitaine, Courbevoie, France No Drawing. Filed Dec. 18, 1968, Ser. No. 784,895 Claims priority, applic1a3gor114grance, Dec. 20, 1967,

Int. (21.15013 1/10 US. Cl. 204-162 XN 8 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION The lamps generally employed for photochemical reactions are mercury vapour discharge lamps.

For many of these reactions, it is necessary to eliminate a part of the radiation which is harmful to the main reaction and responsible for secondary reactions. These secondary reactions produce deposits on the walls of the lamp, reduce the yield of the reaction and contaminate the desired product.

In order to obviate these disadvantages, it has been proposed to employ various filters, in some cases constituted by the very nature of the envelope of the lamp, or to use various products which may be interposed in the path of the radiation through the reaction medium.

GENERAL DESCRIPTION OF THE INVENTION The applicants have designed and produced novel lamps exhibiting a predetermined emission spectrum for various photochemical reactions by means of which it is possible to obtain a pure product in an optimum yield.

It is known that the spectral distribution of the emitted radiation depends essentially upon the nature, upon the quantity and upon the relative proportions of the various elements present in the discharge chamber.

On the other hand, the maximum quantum yield of a particular photochemical reaction may be established as a function of the principal lines of the emission spectrum of a lamp, and the variation of this yield may be established as a function of the concentration and the nature of the reaction medium.

The lamps according to the invention have the advan tage of providing a radiation appropriate for the main reactions in an emission range from 3600 to 6000 A. while substantially reducing the radiation which generates secondary reactions. Thus, in one mode of application of these lamps such as the photochemical preparation of the cycloalkanone oximes and in particular of cyclododecanone oxime, greatly improved yields of the order of 3 to 4 moles kwh. of pure oxime are obtained.

The work carried out by the applicants has involved them in studying, in a first stage, the influence of various 3,681,217 Patented Aug. 1, 1972 addition agents such as the halides of the Groups 6 and 3 of the Periodic System of the Elements taken separately or in admixture as doping agents, and in a second stage in associating them with the halides of the lanthanide group.

The lamps according to the invention are high-pressure mercury vapour discharge lamps optionally containing one or more rare gases, and doped by the introduction into the enclosed space of the lamp of at least one halide of Group 6 of the Periodic System of the Elements, with which there may be associated a halide of Group 3 and/ or a halide of the lanthanide group, the total content of halides being variable from 0.002 mg. to 1 mg./ cc. and preferably from 0.02 to 0.5 mg./cc.

In accordance with one embodiment of the invention, the lamps always comprise a halide of Group 6, such as a chromium halide. They may comprise a mixture of chromium and yttrium halides. Finally, there may be associated with all the aforesaid doping systems a halide of the lanthanide group such as a holmium halide.

When the doping mixture comprises a halide of the metals of Group 6, for example chromium, a halide of the metals of Group 3, for example yttrium, indium and thallium, and a halide of lanthanide, for example holmium, the weight ratio of these halides may be of the order of:

yttrium halide/chromium halide=l/2 holmium halide/ yttrium halide=1/2 In one embodiment of these lamps, mentioned by way of non-limiting example, the doping mixture may consist of:

Mg./cc. Chromium iodide 0200-0250 Yttrium iodide 0100-0125 Holmium iodide 0.05-0.07

It is obvious that the total concentration of the doping mixture and the relative concentrations of the various doping agents may vary to a large extent in accordance with the geometry of the lamp. The geometry of the lamp is in turn chosen with a view to obtaining the maximum radiation power in the reaction system for producing the maximum yield.

These lamps have a radiated-energy yield in relation to the consumed energy which ensures an optimum yield in the photochemical reactions independently of the chemical process employed.

If the emission spectra of these lamps are examined, and for example that of the lamp doped with chromium and yttrium iodides, it is found that the relative power of the radiation below 4000 A. is lower than that of an undoped mercury vapour lamp.

SPECTRAL DISTRHSUTION OF A LAMP CONTAIN- 'ING CHROMIUM AND YTIRIUM IODIDES Energy Relative power of the 7\, A.: radiation, percent 3500-3750 12.47 3750-4000 2.12 4000-4250 11.30 4250-4500 16.70 4500-4750 3.97 4750-5000 1.87

. 3 SPECTRAL DISTRIBUTION OF A MERCURY VAPOUR LAMP Relative power of the A, A.: radiation, percent 3132 0.65

DESCRIPTION OF THE PREFERRED EMBODIMENTS In accordance with one embodiment of the invention, the halogen or halogens may be introduced into the lamp in a form in which they are not combined with'the elements belonging to the aforesaid groups, which are preferably chromium, yttrium, thallium, and holmium. The introduced halogen must be present therein in a proportion at least equivalent to the number of gramme-molecules of the elements of Groups 6 and 3 and of the lanthanides contained in the lamp.

The following examples, which are given by way of indication but have no limiting character will enable the appreciable increases in yield obtained with the lamps according to the invention in various photo-oximation reactions to be appreciated.

By way of comparison, there are first described examples carried out with lamps containing no lanthanide iodide.

EXAMPLE 1 Into a reactor consisting of a cylindrical Pyrex glass receptacle having an internal diameter of 110 mm. and a height of 200 mm., as described in French Pat. 1,331,478, and provided with an undoped mercury vapour lamp of 25 w. enclosed in a Pyrex glass tube, through which a current of cooling Water is passed, are introduced 150 g of cyclododecane in solution in 1650 g. of carbon tetrachloride, and then 50 g. of 99% sulphuric acid. The mixture is stirred and the temperature is maintained between 15 and 20 C. There are introduced 4.3 g. of nitrosyl chloride in solution in carbon tetrachloride and the mercury vapour lamp is ignited.

First after irradiation for 2 hours and again after irradiation for 4 hours, there are introduced 4.3 g. of 10% nitrosyl chloride in carbon tetrachloride (i.e. in all 12.9 g. of nitrosyl chloride).

When the decolouration of the organic solution is complete, which is so after irradiation for 7 hours, the apparatus is stopped, the sulphuric acid layer is separated and the organic solution is then washed with a little 70% sulphuric acid.

The sulphuric acid solutions are combined and poured onto crushed ice. The oxime precipitates and is filtered, washed with water and, after drying, crystallised from cyclohexane. There are thus obtained 35 g. of oxime in 7 hours, which is a yield of 200 g./kwh.

EXAMPLE 2 The procedure of Example 1 is followed with a 25-watt lamp doped with chromium iodide. It is found that it is necessary to introduce 21 g. of nitrosyl chloride in 3 lots in order to decolourise the solution. There are obtained 56.84 g. of cyclododecanone oxime after 7 hours of irradiation, which is a yield of 325 g./kwh.

EXAMPLE 3 The procedure of the preceding examples is followed, substituting a lamp doped with a mixture of chromium and yttrium iodides. It is necessary to introduce 22.5 g.

of nitrosyl chloride in order to decolourise the solution.

' There are obtained 59.5 g. of cyclododecanone' oxime after 7 hours of irradiation, which is a yield of 340 g./kwh.

EXAMPLE 4 Into a reactor consisting of a cylindrical Pyrex glass receptacle having a diameter of 130 mm. and a height of 350 mm., and provided with a stirrer, a thermometer and tubes for the introduction and discharge of gas are introduced 600 g: of cyclododecane in solution in 3000 g. of carbon tetrachloride and 400 g. of 99% sulphuric acid.

The lamp employed is a 75-watt high-pressure mercury.

vapour lamp doped with the mixture of three iodides, i.e. yttrium, chromium and holmium iodide's. It is mounted vertically on the axis of the reactor and in a'Pyrex glass jacket cooled by a current of water. The stirrer is started and the lamp is ignited.

There is then' introduced at a rate of 75 litres per hour. a gaseous mixture of nitrosyl chloride and hydrogen chloride in a mole ratio of NOCl/HCl of 1/ 8.

The temperature is maintained at 15 C., and after irradiation for 6 hours the sulphuric acid layer is decanted and poured onto crushed ice and, after purification, there are recovered 278.4 g. of cylododecanone oxime, M.P. 132 C. The yield is 611.8 g./kwh.

The following Table I will enable the yields obtained with the lamps according to the invention and with undoped lamps to be compared.

TA B LE 1 Cyclododeeanpne Ratio of the Consumpdoped lamp tion undoped kwh. oxime lamp yields The applications of the lamps are not limited to the photo-oximation of cycloalkanes, but include the photooximation of unsaturated hydrocarbons in general.

We claim: I

1. In a process for carrying out a photochemical reaction, especially a process for the production of oximes by exposing a solution of a cycloalkane mixed with sulphuric acid to the radiation of a high pressure mercury vapor lamp and adding nitrosyl chloride to said solution, the improvement comprising increasing the yield of the reaction by using 2. doped high pressure mercury vapor lamp emitting energy having a wavelength lying preponderantly in the range 4000 A. to 6000 A. with at least about 62% of the power of said emitted energy lying in the range 4000 A. to 5750 A. said doped lamp including a doping mixture comprising,

a mixture of at least one Group 6 metal halide, at least one Group 3 metal halide and at least one lanthanide metal halide, the total content of said halides being between about 0.002 mg. and about 1.0 mg. per cubic centimeter.

2. A process according to claim 1 wherein the concentration of the halide of the metal of Group 3 is in a ratio by weight 1/2 in relation to the concentration of the halide of the metal of Group 6 and the concentration of the halide of the metal of the lanthanide group is in a 5. The process according to claim 1 wherein the doping 25,937 medium contains holmium iodide. 3,141,839 6. The process according to claim 1 wherein the doping 3, ,739

medium contains chromium iodide, yttrium iodide and 10 3,309,298 holmium iodide. 3,312,612

7. A process according to claim 1 wherein the photooximation of a cycloalkane is accomplished.

8. The process according to claim 2 wherein the photooximation of a cycloalkane is accompilshed.

References Cited UNITED STATES PATENTS Ito 204-162 0 X Metzger et al. 204-162 0 X Ito 204-162 0 X Ito et a] 204-162 0 X Choo 204-162 0 X BENJAMIN R. PADGETT, Primary Examiner 

